The Science: What is gene drive?

What is gene drive?

Gene drive is a genetic phenomenon that occurs in nature and causes a selected trait to spread rapidly through a species via sexual reproduction over several generations. Gene drive works by increasing the likelihood that a modified gene will be inherited by its offspring. Normally, genes have a 50/50 chance of being inherited, but gene drive How is Target Malaria using systems could increase that chance to upwards gene drive technology? of 99 percent. This means that over the course of several generations, a selected trait could become We aim to tackle malaria at the source. Target increasingly common within a specific species. Malaria is using gene drive approaches to insert a modification in malaria mosquitoes that would Researchers have been studying how to harness affect the mosquito’s ability to reproduce. By gene drives to solve some of society’s most reducing the population of malaria mosquitoes, intractable problems for a long time. Public health we aim to reduce the transmission of the disease. and ecosystem conservation are two of the main areas where research has focused, although other Worldwide there are more than 3,500 species of uses are also possible. mosquito, with 837 of them in Africa. Of these, a single cluster of three very closely related What are gene drive applications species are responsible for most of the malaria transmission – Anopheles gambiae, Anopheles in public health? coluzzii and Anopheles arabiensis.

In public health, several proposals have been The project is investigating the use of genes that made which would use gene drive to limit the produce enzymes (called nucleases) that cut spread of diseases, particularly those spread specific sequences of DNA. The concept for these by insect vectors, such as malaria, which affect nucleases is based on Homing Endonuclease several hundred million people a year. For Genes (HEGs) which are a class of nuclease genes, malaria, this could be done by inserting a trait found in simple single celled organisms, which which makes the mosquitoes unable to host are capable of copying themselves from one the malaria parasite, or one which affects the chromosome to another. local population dynamics of the mosquitoes to reduce their numbers. Two of the main areas we are currently Gene drive approaches to vector control focusing on are biasing the sex ratio represent a potentially highly effective, long term of mosquito populations and reducing and cost-effective tool that could, in the context female fertility. of integrated approaches, help eliminate malaria.

july 2020 targetmalaria.org | [email protected] page 1 of 2 When introduced in the malaria mosquito, the What is the timeline for gene drive nuclease work by identifying and cutting through essential genes targeted by our researchers, such applications for malaria control? as fertility genes. The interrupted gene will no longer function, and modified mosquitoes will be Current research on gene drive is at an early affected according to the nature and importance stage, and so definitive decisions about gene of the gene. drive-based products is premature at best. Based on current progress, products ready for The ultimate goal is to produce modified field testing are 5 years out, possibly longer. malaria mosquitoes that can pass these genes This gives scientists and stakeholders, on to a disproportionately high percentage of particularly those from countries where gene their offspring, so the modification is spread drives might one day be employed, time to throughout the specific population relatively consider the important questions of regulation, quickly and is effectively “self-sustaining”. risk assessment, ethics, and engagement, and to This makes the reduction of the malaria prepare for assessing an actual application. mosquito vector population relatively cost effective and simple to implement because the mosquitoes themselves do the work.

Gene drives increase gene spread

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